While VOO provides broad market exposure, MGK targets only mega-cap stocks. Here's how they stack up.The Vanguard Mega Cap Growth ETF (MGK +0.78%) and the Vanguard S&P 500 ETF (VOO +0.36%) differ most in their sector concentrations, dividend yields, and long-term risk-return profiles.Both MGK and VOO are Vanguard funds, but MGK zeroes in on the largest U.S. growth stocks, while VOO tracks the full S&P 500 -- offering exposure to a broader array of top U.S. companies. This comparison spotlights key differenc ...